Basic hookup

As I plan to make a custom breakout board I wanted to solder as few connections as possible.
I was able to boot the device, with UART (out at least) soldering the following.

PIN

NAME

0

GND

1

3V3

2

EN

15

GND

34

RXD

35

TXD

38

GND

Note I did not solder/reflow/hotair the central GND

Flashing

In order to flash without having to press button or jump jumpers I wanted to use DTR/RTS
from the UART to toggle EN and enable flash upload mode. Two more pins are required.

PIN

NAME

UART

25

IO0

DTR

24

IO2

x

2

EN

RTS

GPIO2 can be left connected to GND if not being used, but otherwise needs to be
connected to GND in order to boot into flash upload mode.

GPIO0 on the otherhand, must be connected to 3V3 in order to boot, and connected
to GND in order to boot into flash upload mode. Connect to DTR on the UART module.

EN shoud be connected to RTS.

Flash tool

The old esptool.py will not work on the ESP32, there is a more up to date version available
on the ESP32 forums, registration may be required. Link: esptool32.py

SDK

So far this is definitely the most beta part of working with the ESP32.
Just a simple comparison of the linker linker scripts from this and the ESP8266
shows only about 10% of the functionality is available, not including new
features unique to the ESP32.

GPIO

Cannot seem to configure GPIO23 as an output. 21 and 22 worked fine.

Bad Boot

At some point I ended up with the bootloader in a bad state and not matter how I reflashed I got the following error

Several things happen or where done around the time this problem started. The most notable for
me is the multimeter probes connacting each other shorting out the circuit. With my limit
electronics knowledge I'm unsure how bad of a problem this is. The circuit was layed out with
5V going through the meter, then connected to an LD33V which powered the board.

Some progress

I've been flashing with -fs 2m without problems so far. After this issue I've dropped that,
letting esptool32 default to 4m which has let the boot loader progress.

Question: With the power connected as I have it (5V -> multimeter -> LD33V -> ESP32), what is the potential for damage if I short 5V to ground? If not damage inducing, what effect could this have on the Flash?

Edited 1 time

Nov 6, 2016

I just received esp32 wroom32 and find your information very good. It seems it has everything to created my own working PCB to start with Wroom32 (ordered with Olimex).
Can you a bit clarify this: "GPIO2 can be left connected to GND if not being used, but otherwise needs to be connected to GND in order to boot into flash upload mode." it sounds strange like: "it must be connected to GND and otherwise it needs to be connected to GND"?

Have you been able to make your PCB - can you post schematics and pcb?